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(ModeL) I G. .P. BULEN.

THERMOSTATIG OIRGUIT CLOSER. No. 333,443. Patented Dec. 29. 1885.

' Inventor:

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- 1 UNITED STATES l PATENT OFFICE.

GEORGE F. BULEN, or JERSEY oirr, NEW JERSEY, ASSIGNOR To 'THE an TOMATICFIRE ALARM AND EXTINGUISHER NEW YORK, N. Y;

COMPANY, (LIMITED,) OF

TH EiiMO-STATIC Cl RCUlT-CLOSER.

SPECIFICATION fonning part of Letters Patent No. 333,443, dated December29, 1885.

Application filed June 14, 1882. Serial No. 64,144. (Modeh) To all whomit may cofwern:

Be it known that I, GEORGE F. BULEN, a citizen of the United States, anda resident of Jersey City, in the con nty of Hudson and Stateof NewJersey, have invented a new and useful Improvement. in ThermostaticCircuitClosers, of which the following is a specification.

The. object of my invention is to provide a thermostat which will bereadily afl'ect'ed by slight changes of temperature, and will by itsexpansion complete an electric circuit under the influence of anypredetermined degree of heat, and to construct the. same in a manneradapted to secure uniformity of action and freedom from the injuriouseffects due to the continuallymecurring expansio-nand contractraction ofthe metals of which it is composed.

My invention consists in supporting a thermostatic strip in a novelmanner upon a peculiar form of base-plate, and in providing convenientmeans for covering the same, securing electrical connections therewith,and for supporting a contact-point for completing a circuitby the actionof the thermostatic strip.

1n the accompanying drawings, Figure 1 is a plan view of the exterior ofa thermostat embodying my improvements. Fig, 2 is a cross-section of thesame; and Fig. 3 is a plan showing the working parts of the apparatus,with the top or cover removed.

Referring to these figures, A represents a a metallic base forsupporting the various parts of the instrument.

Two binding-screws, a and a, are mounted on opposite sides of theinstrui-uent, for convenience in attaching electric conductors thereto.The binding-posta is in electrical connection with the metallic base A,while the post a is insulated therefrom by means of suitable washers, bb, of hard rubber, porce- The thermostatic coil consists of two flatpieces of metal, 0 and 0', (see Figs. 2 and 3,) having differentcoefiicient's of expansion sccurcly brazed together and formed into aninvolutc curve. The strip of metal 0. upon the inner side of the curve,is preferably of iron, while the outer strip, 0', is of brass or othermaterial having a coefiicieut' of expansion about twice that of theinner strip, and is also double the thickness of the strip 0. The innerend of the compound strip, which is situated at the origin a of thespiral is supported from the base A, by means ofa screw, D, ex 5 tendingthrough a metallic collar, (i, into anaperture, d. in one side of-whichthe end a is secured by brazing, soldering, or otherwise. The outer orfree end of the curved strip is provided with a contact-point, 6',preferably faced with platinum to prevent corrosion. At; a point beyondthe normal position of this coutact-point and directly in the line ofthe extended curve is supported a contact-stop, against which the pointe impinges, as here- 6 in'after explained. when the thermostat isinfluenced by a snh'icient increase of temperature, This contact-stopconsists of a platinum point, 0, supported upon an adjustable screw, E,which is mounted in. a post, E. The post E is insulated from the base Ain the same manner as has already been described with reference to thebindingpost a, to which binding-post it is united by a suitablecouducting-strip, e. The contact-points e and e are normally separated ashort distance from each other, and this distance may be accuratelyadjusted by means of the movable screw E.

When for any reason the temperature in the building or room containingthe thermostat increases or diminishes, the metals composing thesection-strips c and c expand or contract accordingly, but in differentratios, and the ratio of expansion of the outer strip being greater thanthat of the inner, the point 6 will be advanced toward the contact-pointa under the influence of an increase of temperature, and will be in likemanner withdrawn when the temperature is decreased. It is evident,thcrefore,that the position of the contact-point 0 e may be so adjustedthat the circuit will be completed between the points e and a under theinfluence of any predetermined degree of heat, and hence by includingthe two points in an electric circuit containing a signaling 5 apparatusan alarm may be automatically actuated thereby in a well-known manner.The terminal wires of such a circuit are shown at W? in Fig. 1, and theapparatus may be united directly therewit-hat the binding-screws a anda; or through the medium of short connecting-wires w w.

Over the top of the instrument and inclosing the thermostatic coil isfitted a cap or cover, H, of thin metal or other suitable material. Thiscover is preferably convex in shape, and has recesses formed in itsedges, as shown, which fit over the lateral lugs supporting thebindingposts a and a'.' The cover is ofspun metal, and is preferablysecured in position by being fitted tightly over the edge or rim of thebase A, but it; may be secured by screws or other suitable means.

For the purpose of protecting the instrnment, when necessary, frommoisture or dust, I provide an outer protector orshie-ld, G,which issupported from the base A by means of a screw, g, which screw ispreferably provided with a shoulder, g, to prevent the shield G fromcoming into contact with the two binding screws (1 and a, and therebyshort-circuiting the thermostat.

I claim as my inyentiou- 2- 1. In a thermostat, the combination,substantially ashereinbefore set forth, of athermo static strip, ametallic plate for supporting the same, a collar having an aperture inwhich said strip is brazed or soldered, a screw extending through saidcollar into said base and uniting said strip and-collar thereto, and aninsulated contact-point applied to the remaining end of said strip.

2. The combination, substantially as hereinbefore set forth, of a,thermostatic strip, a.

metallic base for supporting the same, an insulated screw carried uponsaid base, an adjnstabie contact-screw extending through a longitudinalopening in said insulated screw into proximity to the end of said strip,and a;

convex spun-metal cover fitting over said strip and contact-point.

3. The combination, substantially as here: inbefore set forth, of athermostatic strip, a

metallic base-plate, an insulated screw support-ed upon the same havinga horizontal opening through the same, a contactpin or,

screw extending through said opening, means for connecting one end ofthe strip to said base, and a cover, H, for said strip.

4. The combination, substantially as hereinbefore set forth, of athermostatic strip, the metallic base 21, having lateral iugs, thescrews a and a, respectively supported upon said lags, one of whichscrews is insulated from said base, and a cover, H, for said strip,having recess-es formed in its edges for receiving said lugs.

In testimony whereof I have hereunto sub scribed my name this'9th day ofJune, A. D. 1882.

scones F. Bonn Witnesses:

CHARLES AaTBRRY, D. W. Eoceoosra

